The present invention relates to soap dispensers of the kind found in public washrooms and in other types of washrooms, for example scrub rooms in hospitals, where the dispenser is to be operated without hands-on or manual control. The soap dispenser is operated by a sensor, for example infrared, and will provide a measured amount of soap when the hands of the person desiring the soap are placed within the path of the sensor. Since soap is supplied in various viscosities, depending upon the particular application, and since it is important that the soap not be splashed when dispensed, there is a viscosity or thickness control to accommodate soaps of different viscosity. There is also a timing circuit which controls the volume of soap or the time during which the pump will actually dispense soap. Further, the invention includes a priming circuit to prime the pump as required.
The invention is described particularly in connection with a soap dispenser, although it has application in any environment in which it is desired to dispense a liquid having a viscosity greater than that of water and in which it is desired to control the force at which the viscous liquid is dispensed and also the time period of operation. In this context, the invention has application in the dispensing of condiments such as ketchup, mustard, salad dressing, etc., and in dispensing cosmetic products such as shampoo, lotion, and conditioners, etc.